For years, genealogists and family historians have pored over the massive green and maroon ledgers at the Family Records Centre in London, searching for details of more than 150 years of births, marriages and deaths. But there was anger or outright incredulity this weekend as professional and amateur researchers arrived to find most of the shelves bare.

There will never again be public access to the paper records, the index to where in the country all the births, marriages and deaths were registered, but - as so often with government IT projects - the timetable for the online version intended to replace them has collapsed. According to a spokesman for the Office for National Statistics, which is responsible for the General Records Office, "the present target is to have the online index available by mid-2009".

In the meantime, researchers are invited to use microfiche, which means, one furious researcher said, that "not even God himself is going to be able to find most of this stuff". "It's an absolute disgrace," said Norman and Audrey Medcalf, who set out two years ago on the trail of an absurdly romantic family history of emigration and shipwreck. "This is going to be such a loss to family historians; there is no substitute for the paper records, and there's also the company of other researchers here, people sharing their search tips."

The work of digitising the records was contracted out by Siemens to India, and has fallen far behind. The most cursory glance at the paper records reveals the problem of microfiche. By mid-December 1856 the clerk with the childish round hand was clearly running short of office ink: the line recording that the marriage of Margaret Hayhurst was registered in Bury is barely legible, and would be completely illegible when magnified from a tiny image on an acetate sheet and projected on to a grimy grey-on-grey screen.

Pauline Pearson, a retired ballet dancer, is tracking down the working-class background her middle-class mother always struggled to conceal. She is back now to the youngest of 13 children of a Lancashire cotton weaver who walked away from his loom, never spoke to, or of, his family again, but died a company director and leading freemason. Ms Pearson said: "For many older people who are not computer-literate ... this is the end of the line."

"It's deplorable," said Maggie Loughran, administrator of the Federation of Family History Societies. "The removal of the paper records and the closure of these facilities is happening ahead of time, but nobody knows when the digital version will be available."

Sarah Williams, editor of the new BBC magazine Who Do You Think You Are?, launched on the back of the success of the television series and the growing craze for amateur genealogy, said: "The sweetener was that the paper records would be replaced by a superior digital version. But to lose one before the other is ready is a highly questionable decision."

The Medcalfs, from Enfield, have been researching Mr Medcalf's great-great-uncle, a grocer from Ware who emigrated to Australia with his seven children, was shipwrecked in 1853, rescued with his wife and family by a whaler and brought to Mauritius, and finally made it to a prosperous life in Australia, from where he sent back the vivid description of his adventures inherited by Norman Medcalf's father.

The ledgers - the oldest of them hand-written on parchment - are trundling off to a store in Christchurch, Dorset, and in theory, all the Medcalfs on record should already be available through an online system. But the internal system which will allow the statistics office to access its own files digitally is at least a year off, the public system probably twice that.

The Family Records Centre opened only 10 years ago, shared between the ledgers of the General Records Office on the ground floor - now closed - and a first-floor reading room operated by the National Archives at Kew. Four complete sets of the microfiche index are being made available in the National Archives space until March, when the whole building will close to the public and researchers will have to work online.

A statement from the Office for National Statistics said: "When our project to create a massive online index of 250 million births, marriages and deaths is complete, it will dramatically improve public access to information of interest to family historians."